Outline

Introduction: The purpose of this study was to identify in-vivo the effectiveness of the two most frequently used autografts (semitendinosus/gracilis [ST/G] and bone-patellar tendon-bone [BPTB]) for ACL reconstruction, in restoring tibial rotation to normal physiological levels.

Methods: Eleven patients ACL reconstructed with a BPTB graft, eleven patients ACL reconstructed with an ST/G graft and eleven controls were assessed. Kinematic data were collected (50Hz) with a six-camera optoelectronic system, while the subjects descended stairs and immediately after, pivoted on their landing leg. The dependent variable examined was the tibial internal-external rotation during pivoting. All patients in both groups were also assessed clinically and with the use of a KT-1000 to evaluate anterior tibial translation.

Results: The results demonstrated that reconstructions with either graft, successfully restored anterior tibial translation. The statistical analysis though, that was performed between the three groups for the dependent variable, showed the existence of significant differences among the groups (p=0.001). The post-hoc comparisons revealed that both ACL reconstructed groups had significantly increased tibial rotation when compared with the control, while no significant differences were observed between the two reconstructed groups. The intact knees for both reconstructed groups had similar values of tibial rotation with the control.

Conclusions: Therefore, we found that neither graft is able to restore tibial rotation to normal levels. This conclusion gives further support to the in-vitro findings by Woo et al, that even though the two grafts are successful in limiting anterior tibial translation, none of them is effective in reducing tibial rotation. Current ACL reconstruction techniques using BPTB and ST/G grafts, anchored in one femoral and one tibial tunnel, seem to only partially achieve the goal of actual reinstatement of the true two-bundle anatomy of the ACL. Our results may also provide an intriguing explanation regarding the development of future pathology. It is possible that this increased tibial rotation could result in the application of loads at areas of the cartilage and are not commonly loaded in a healthy knee. Over time this could lead to knee osteoarthritis. The improvement and development of new surgical techniques that can better approximate the actual anatomy and function of the ACL may be able to provide a solution to this problem.